Intradialytic use of sodium thiosulfate

ABSTRACT

Provided herein are methods for maintaining physiological levels of thiosulfate in a subject undergoing hemodialysis. Also provided herein are methods of administering pharmaceutically acceptable sodium thiosulfate to a subject undergoing hemodialysis.

CROSS REFERENCE

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/468,871, filed Mar. 8, 2017, the content ofwhich is incorporated herein by reference in its entirety.

FIELD

Provided herein are methods for maintaining physiological levels ofthiosulfate in a subject undergoing hemodialysis. Also provided hereinare methods of administering pharmaceutically acceptable sodiumthiosulfate to a subject undergoing hemodialysis.

BACKGROUND

Patients with chronic kidney disease (CKD) experience deterioration ofkidney function which results in a reduction in the excretion ofmetabolic waste products. The accumulation of metabolic waste productscan become life threatening within days. Patients with little or noresidual kidney function are characterized as having “end-stage renaldisease.” Therefore, such patients need an alternative means to excretewaste products to survive. Dialysis is a means to excrete waste productsthat involves the transfer of waste products from the blood to anexternal liquid that is subsequently discarded (Am. J. Kidney Dis. 2002,39(Suppl. 1), S1-266).

Dialysis is defined as the movement of solutes and water between twoliquids that are separated by a semipermeable “dialyzer membrane.” Inhemodialysis, blood flows across one side of the dialyzer membrane whilea water-based solution called dialysate flows across the other side.Dialyzer membranes contain pores through which solutes can pass. Theconcentrations of solutes that are present in these two liquidsequilibrate as osmotic forces push them out of the high concentrationliquid, through the dialyzer membrane pores, and into the lowconcentration liquid.

Dialyzer membranes are designed with different pore sizes to limit thesolutes that can pass through during hemodialysis. During hemodialysis,it may be harmful to remove from the blood an excessive amount of smallmolecule solutes, which can diffuse through dialyzer membrane.

Blood contains small molecular weight solutes such as thiosulfate (S₂O₃²⁻). Thiosulfate anions have a molecular weight of approximately 112.13Daltons. In the body, thiosulfate converts small amounts of cyanide ioninto harmless products. Thiosulfate can also be metabolized to sulfate(SO₄ ²⁻) (Gunnison et al., Environ. Res. 1981, 24, 432-443; Skarzynskiet al., Nature 1959, 184, 994-995).

The Association for the Advancement of Medical Instrumentation (AAMI)established a quality specification limit for the sulfate content inwater that is used in dialysis (maximum 100 mg per liter, i.e. 100 ppm)(#ANSI/AAMI/ISO 13959:2009). The AAMI also specified that the sulfatecontent in water should be measured using the “turbidimetric method”. Inthis method, sulfate ion is precipitated in an acetic acid medium withbarium chloride so as to form barium sulfate crystals of uniform size.Light absorbance of barium sulfate suspension is measured by aphotometer and the sulfate anion concentration is determined bycomparison of the reading with a standard curve (American Public HealthAssociation. Available online athttps://law.resource.org/pub/us/cfr/ibr/002/apha.method.4500-so42.1992.pdf).This test method does not distinguish between sulfate and thiosulfate.Instead, it is actually a measurement of both sulfate and thiosulfate.Therefore, the AAMI quality specification for sulfate is actually alimit of the sum of sulfate and thiosulfate in water that is used indialysis.

Coronary bypass patients have decreased plasma thiosulfate levels(Ivankovich et al., Anesthesiology 1983, 58, 11-17). Coronary arterybypass surgery is often advised for patients with cardiovascular diseasethat is characterized by significant narrowings and blockages of theheart arteries caused by atherosclerosis. Atherosclerosis is a chronicinflammatory condition that begins with the formation of calcifiedplaque inside the vascular wall in large and mid-sized arteries. Calciummineralization of the lumen in the atherosclerotic artery promotes andsolidifies plaque formation causing narrowing of the vessel (Kalampogiaset al. Med. Chem. 2016, 12, 103-113). Atherosclerotic plaques can causesignificant narrowing in one or more coronary arteries. Myocardialinfarction occurs when blood flow within a coronary artery is completelyobstructed by an atherosclerotic plaque.

Cardiovascular disease accounts for more than half of all deaths ofpatients who require chronic hemodialysis (Go et al., N. Eng. J. Med.2004, 351, 1296-1305).

There was a 1.7 fold increased risk of sudden death events in the 12hour period beginning with the dialysis treatment. Sudden death eventswere increased both during the dialysis procedure itself and aftertreatment (Bleyer et al., Kidney Int. 2006, 12, 2268-2273).

Coincidentally, the concentration of thiosulfate in the plasma declinesby over 60% during the first hour of hemodialysis and remainssignificantly depressed during the subsequent hours of a four-hourhemodialysis session. (Freise et al., Free Radic. Biol. Med. 2013, 58,46-51)

Sodium thiosulfate can be administered into the blood by intravenousinjection; however, it would be ineffective in maintaining physiologicallevels with dialysis patients since it is rapidly removed duringhemodialysis. At this time, there is no effective method for maintainingphysiological levels of thiosulfate in the blood of patients who undergohemodialysis. There is also no satisfactory method for administratingsodium thiosulfate to patients during hemodialysis.

SUMMARY

The present disclosure provides methods for maintaining physiologicallevels of thiosulfate in a subject undergoing hemodialysis. The presentdisclosure also provides methods for preventing atherosclerosis,myocardial infarction, sudden cardiac death, stroke, cardiovasculardisease, high blood pressure, pulmonary hypertension, and/or renalhypertension in a subject undergoing hemodialysis. The presentdisclosure also provides methods for administering sodium thiosulfate ina subject undergoing hemodialysis.

In some embodiments, provided herein are methods for maintainingphysiological levels of thiosulfate in a subject undergoinghemodialysis, comprising intradialytically contacting said subject'sblood with a dialyzer membrane that is also in contact with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, also provided herein are methods for maintainingphysiological levels of thiosulfate in a subject undergoinghemodialysis, comprising intradialytically contacting said subject'sblood with a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to an unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, also provided herein are methods for preventingatherosclerosis in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, also provided herein are methods for preventingmyocardial infarction in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, also provided herein are methods for preventingsudden cardiac death in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, also provided herein are methods for preventingstroke in a subject undergoing dialysis, comprising intradialyticallycontacting said subject's blood with a dialyzer membrane that is also incontact with a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, also provided herein are methods for preventingcardiovascular disease that is characterized by tissue ischemiaincluding angina, cerebral vasospasm, claudication, critical limbischemia, peripheral vascular disease, and sickle cell crisis in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a dialyzer membrane that is also in contactwith a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, also provided herein are methods for preventinghigh blood pressure, pulmonary hypertension, and renal hypertension in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a dialyzer membrane that is also in contactwith a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, also provided herein are methods for administeringsodium thiosulfate to a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a schematic diagram of elements of the flow path of thedialysate, the blood of patients, and the aqueous solution comprisingsodium thiosulfate. (10) Dialysis machine; (20) acid concentratesolution; (30) bicarbonate concentrate solution; (40) aqueous solutioncomprising sodium thiosulfate; (50) flow of aqueous solution comprisingsodium thiosulfate; (60) dialysate tubing; (70) valve; (80) dialyzer;(90) dialyzer membrane; (100) detection point “pre” dialyzer membrane;(110) detection point “post” dialyzer membrane; (120) detection point“V”; (130) detection point “A”; (140) used dialysate.

DETAILED DESCRIPTION

The following detailed description is not to be taken in a limitingsense, but is made merely for the purpose of illustrating theembodiments provided herein.

To facilitate understanding of the disclosure set forth herein, a numberof terms are defined below.

Generally, the nomenclature used herein and the laboratory procedures ininorganic chemistry, analytical chemistry, organic chemistry, medicinalchemistry, and pharmacology described herein are those well known andcommonly employed in the art. Unless defined otherwise, all technicaland scientific terms used herein generally have the same meaning ascommonly understood by one of ordinary skill in the art to which thisdisclosure belongs. In the event that there is a plurality ofdefinitions for a term used herein, those in this section prevail unlessstated otherwise.

The term “subject” refers to an animal, including, but not limited to, aprimate (e.g., human), cow, sheep, goat, horse, dog, cat, rabbit, rat,or mouse. The terms “subject” and “patient” are used interchangeablyherein in reference, for example, to a mammalian subject, such as ahuman subject. In one embodiment, the subject has or is at risk for adisease, disorder or condition provided herein. In another embodiment,the subject has or is at risk for a disease, disorder or conditionwherein the disease, disorder or condition, or a symptom thereof, can betreated, prevented or ameliorated by the administration of sodiumthiosulfate. In another embodiment, the subject is an end stage renaldisease (ESRD) patient who is placed on regular hemodialysis. In anotherembodiment, the subject is a patient with some or no renal function whoundergoes dialysis to reduce wastes from the blood to safe levels. Inanother embodiment, the steady-state plasma concentration of thiosulfatein the subject undergoing hemodialysis is significantly reduced as aresult of about 3 to about 5 hours of hemodialysis. In anotherembodiment, the subject has plasma levels of thiosulfate that are belownormal physiological levels.

The terms “treat,” “treating,” and “treatment” are meant to includealleviating or abrogating a disorder, disease, or condition, or one ormore of the symptoms associated with the disorder, disease, orcondition; or alleviating or eradicating the cause(s) of the disorder,disease, or condition itself.

The terms “prevent,” “preventing,” and “prevention” are meant to includea method of delaying and/or precluding the onset of a disorder, disease,or condition, and/or its attendant symptom(s); barring a subject fromacquiring a disease; or reducing a subject's risk of acquiring adisorder, disease, or condition.

In general, conventional dialysates are defined as any formulationheretofore known, whether or not proprietary, including those that arerecently patented. Many of these are specially formulated to satisfy theneeds of a particular type. For example, U.S. Pat. No. 6,436,969discloses compositions containing AGE inhibitors, U.S. Pat. No.5,869,444 claims solutions contain an osmotically effective mixture ofpeptides, U.S. Pat. Nos. 6,306,836 and 6,380,163 disclose peritonealdialysis solution utilizing amino acids to achieve osmotic balance.

The term “bicarbonate concentrate solution” refers to aqueous solutioncomprising a bicarbonate salt or a mixture of bicarbonate salts andwater that meets or exceeds the current hemodialysis water qualitystandards as listed in ANSI/AAMI/ISO #13959:2009 (hereafter called“purified water”). Minntech Renal Systems in Minneapolis, Minn. suppliesCentrisol® Bicarbonate Concentrate Powder MB-330. Each bag of Centrisol®Bicarbonate Concentrate Powder 45X MB-330 contains about 650 grams ofsodium bicarbonate. The contents of a bag are mixed with purified waterto make about 8 liters of dialysate bicarbonate concentrate solution.

The term “acid concentrate solution” refers to aqueous solutioncomprising acid or a mixture of acids and purified water. Representativeexamples of acid include, but are not limited to hydrochloric acid,acetic acid, citric acid, and peracetic acid. Minntech Renal Systems inMinneapolis, Minn. supplies Centrisol® Acid Concentrate 45X SB-111. Eachbag of Centrisol® Acid Concentrate Powder 45X contains acetate,bicarbonate, calcium, chloride, dextrose, magnesium, and potassium. Onevolume part of acid concentrate should be mixed with 1.72 volume partsof properly mixed MB-330 Series Sodium Bicarbonate Concentrate and 42.28volume parts of purified water to prepare 45 volume parts of dialysatesolution.

The term “dialysis machine” is a machine comprising an extracorporealcircuit and a dialysate circuit. The extracorporeal circuit furthercomprises tubing, blood pump, heparin pump, kidney, and monitors forblood flow, blood pressure, and air bubbles. The dialysate circuitfurther comprises dialysate tubing, dialysate pump, and monitors fordialysate flow, dialysate pressure, and air bubbles. Presently, dialysismachines utilize an automated proportioning system to mix the acidconcentrate solution, bicarbonate concentrate solution and purifiedwater in specific proportions to general the dialysate. The dialysateconcentrate solutions (acid and bicarbonate) are usually supplied by themanufacturer either as a premixed powder (as bicarbonate powder) that isadded to purified water in large reservoirs or as a solution (as acidconcentrate) ready to use. The dialysate concentrate solutions arepumped into a chamber in the dialysis machine where they are mixed withpurified water to make the dialysate.

The term “dialysate tubing” refers to the tubing connects a dialysismachine and a dialyzer.

The term “dialyzer” is meant to include an artificial kidney comprisinga synthetic or semi-synthetic semipermeable membrane (hereafter called“dialyzer membrane”) made of chemical materials including but notlimited to cellulose acetate, cupraphane, polyacrilonitrile, polymethylmethacrylate, or polysulfone. A constant flow of blood on one side themembrane and dialysate on the other allows removal of wastes in theblood. An artificial kidney can be used to perform hemodialysis, duringwhich diffusion is the major mechanism for solute removal. On the otherhand hemofiltration (also called hemodiafiltration and diafiltration)relies on ultrafiltration and convective transport rather than diffusionto move solutes across a high porosity semipermeable membrane.

The term “unspiked dialysate” refers to the dialysate solution mixed bythe dialysis machine and pumped into the dialysate tubing to flow to thedialyzer membrane before the aqueous solution comprising sodiumthiosulfate is added to the dialysate tubing through a valve.

The term “thiosulfate-spiked dialysate” refers to dialysate solution inthe dialysate tubing after the aqueous solution comprising sodiumthiosulfate is added to the dialysate tubing through a valve.

The term “therapeutically effective amount” is meant to include theamount of a compound that, when administered, is sufficient to preventdevelopment of, or alleviate to some extent, one or more of the symptomsof the disorder, disease, or condition being treated. The term“therapeutically effective amount” also refers to the amount of acompound that is sufficient to elicit the biological or medical responseof a cell, tissue, system, animal, or human, which is being sought by aresearcher, veterinarian, medical doctor, or clinician. In oneembodiment, a therapeutically effective amount is an amount sufficientto maintain a subject's blood level of thiosulfate at aboutphysiological levels.

The term “about” or “approximately” means an acceptable error for aparticular value as determined by one of ordinary skill in the art,which depends in part on how the value is measured or determined. Insome embodiments, the term “about” or “approximately” means within 1, 2,3, or 4 standard deviations. In some embodiments, the term “about” or“approximately” means within 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%,1%, 0.5%, or 0.05% of a given value or range. In some embodiments, it iscontemplated that the values preceded by the term “about” or“approximately” are exact.

The term “normal physiological levels” of thiosulfate means the levelsof thiosulfate that occur in a healthy adult subject. In one embodiment,the normal physiological level of thiosulfate in a subject is between 1and 10 micromolar.

In some embodiments, the methods provided herein comprise the use ofpurified forms of sodium thiosulfate, such as sodium thiosulfatepentahydrate (Na₂S₂O₃.5H₂O). In one embodiment, provided herein ispharmaceutical grade sodium thiosulfate. In another embodiment, providedherein are forms of sodium thiosulfate meeting or exceeding one, morethan one or all FDA standards for sodium thiosulfate for pharmaceuticaluse. In another embodiment, provided herein are forms of sodiumthiosulfate that were manufactured according to Good ManufacturingPractices (GMP) as detailed in the United States Code of FederalRegulations 21 CFR 211. In one embodiment, the pharmaceuticallyacceptable sodium thiosulfate is that disclosed in U.S. Pat. Pub. No.2011/0008467, filed Jul. 7, 2010, which is incorporated by referenceherein in its entirety.

In one embodiment, the sodium thiosulfate is solid.

In one embodiment, the appearance of the sodium thiosulfate is colorlesscrystals.

In one embodiment, the appearance of a 10% solution containing thesodium thiosulfate is clear and colorless.

In one embodiment, the sodium thiosulfate is odorless.

In one embodiment, the presence of sodium thiosulfate in a 10% solutioncontaining sodium thiosulfate provided herein is identified by thedischarge of yellow color after the addition of a few drops of iodineTS.

In one embodiment, the presence of sodium in sodium thiosulfate providedherein is confirmed according to Method 191 in USP XXXII (2009), whichis incorporated by reference herein in its entirety.

In one embodiment, the presence of thiosulfate in sodium thiosulfateprovided herein is confirmed according to Method 191 in USP XXXII(2009).

In one embodiment, the sodium thiosulfate pentahydrate provided hereincontains no less than about 99% by weight and/or no greater than about100.5% by weight of sodium thiosulfate calculated on the anhydrousbasis. In some embodiments, the amount of anhydrous sodium thiosulfatein the sodium thiosulfate pentahydrate provided herein is determinedaccording to USP colorimetric assay (USP XXXII (2009)).

In one embodiment, the sodium thiosulfate pentahydrate provided hereincontains no less than about 98% by weight and no greater than about 102%by weight of sodium thiosulfate on an anhydrous basis as measured by ionchromatography.

In one embodiment, the sodium thiosulfate pentahydrate provided hereincontains no less than about 98% by weight and/or no greater than about102% by weight of sodium thiosulfate calculated on the anhydrous basis.In some embodiments, the amount of sodium thiosulfate anhydrous in thesodium thiosulfate pentahydrate provided herein is determined by an ionchromatography. In some embodiments, the amount of anhydrous sodiumthiosulfate in the sodium thiosulfate pentahydrate provided herein isdetermined by an ion chromatography with electrochemical conductivitydetection as described herein.

In another embodiment, the sodium thiosulfate provided herein has a pHbetween about 6 to about 8 when measured in a 10% solution at 25° C. Insome embodiments, the pH of the sodium provided herein is measured usinga pH meter. In some embodiments, the pH of the sodium thiosulfateprovided herein is determined according to Method 791 in USP XXXII(2009).

In yet another embodiment, the sodium thiosulfate provided herein haswater content of about 32% to about 37% by weight. In some embodiments,the water content in the sodium thiosulfate provided herein isdetermined by Karl Fischer method. In some embodiments, the watercontent in the sodium thiosulfate provided herein is quantitatedaccording to Method 921 in USP XXXII (2009).

In yet another embodiment, the heavy metal content in the sodiumthiosulfate provided herein is no greater than about 10 ppm of a heavymetal. The heavy metal content in the sodium thiosulfate provided hereinis determined according to Method 231 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.02% by weight of carbonate. In yetanother embodiment, the sodium thiosulfate provided herein contains nogreater than about 0.01% by weight of carbonate. In some embodiments,the amount of carbonate in the sodium thiosulfate provided herein isdetermined by contacting a sodium thiosulfate sample with an acid, suchas phosphoric acid, to convert carbonate to carbon dioxide anddetermining the amount of the carbon dioxide using a non-dispersiveinfrared detector.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.005% by weight of insoluble matter. Insome embodiments, the amount of insoluble material in the sodiumthiosulfate provided herein is determined by dissolving 10 grams of thesodium thiosulfate provided herein in 100 mL of water, the solution isheated to boiling for 1 hr, the solution is filtered, washed with hotwater, dried, cooled in a desiccator, and weighed.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 200 ppm by weight of chloride. In someembodiments, the chloride content in the sodium thiosulfate providedherein is determined according to Method 221 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.002% by weight of iron. In someembodiments, the iron content in the sodium thiosulfate provided hereinis determined using inductively coupled plasma mass spectrometry(ICP-MS). In some embodiments, the iron content in the sodiumthiosulfate provided herein is determined using inductively coupledplasma-optical emission spectroscopy (ICP-OES). In some embodiments, theiron content in the sodium thiosulfate provided herein is determinedaccording to Method 241 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.001% by weight of lead. In someembodiments, the lead content in the sodium thiosulfate provided hereinis determined according to Method 251 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.01% by weight of calcium. In someembodiments, the calcium content in the sodium thiosulfate providedherein is determined using ICP-MS. In some embodiments, the calciumcontent in the sodium thiosulfate provided herein is determined usingflame emission spectrometry (FES).

In yet another embodiment, the sodium thiosulfate provided herein causesno turbidity when ammonium oxalate test solution prepared according toUSP XXXII (2009) is added to an aqueous solution containing sodiumthiosulfate (e.g., one gram of sodium thiosulfate dissolved in 20 mL ofwater).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.005% by weight of potassium. In someembodiments, the potassium content in the sodium thiosulfate providedherein is determined using ICP-MS. In some embodiments, the potassiumcontent in the sodium thiosulfate provided herein is determined usingFES.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.05% by weight of sulfite, or no greaterthan about 0.1% by weight of sulfite. In some embodiments, the sulfitecontent in the sodium thiosulfate provided herein is determinedaccording to the method for the determination of sulfite in AmericanChemical Society, Reagent Chemicals, 10^(th) Edition, incorporated byreference herein in its entirety.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.05%, no greater than about 0.1%, nogreater than about 0.25%, or no greater than about 0.5% by weight ofsulfate (as SO₄ ²⁻). In some embodiments, the sulfate content in thesodium thiosulfate provided herein is determined according to the methodfor the determination of sulfate in American Chemical Society, ReagentChemicals, 10^(th) Edition.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.001% by weight of sulfide. In someembodiments, the sulfide content in the sodium thiosulfate providedherein is determined by the addition of lead (II) nitrate using methodsdescribed herein.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.002% by weight of nitrogen compounds(as N). In some embodiments, the nitrogen compounds (as N) content inthe sodium thiosulfate provided herein is determined according to themethod for the determination of nitrogen compounds in American ChemicalSociety, Reagent Chemicals, 10^(th) Edition.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 10 ppm, no greater than about 100 ppm, nogreater than about 500 ppm, no greater than about 1000 ppm, or nogreater than 5000 ppm of total volatile organic carbon. In someembodiments, the sodium thiosulfate provided herein contains no greaterthan the specific limits set forth in ICH Q3C(R3) for organic volatileimpurities or a particular solvent (e.g., ethanol), the disclosure ofwhich is incorporated by references in its entirety. In someembodiments, the content of organic volatile impurities is determinedaccording to Method 467 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains total NPOC of no greater than about 60 ppb, no greater thanabout 2.5 ppm, no greater than about 8 ppm, no greater than about 10ppm, no greater than about 20 ppm, no greater than about 25 ppm, or nogreater than about 50 ppm. In some embodiments, the sodium thiosulfateprovided herein contains total NPOC of no greater than about 12 ppm. Insome embodiments, the total NPOC in the sodium thiosulfate providedherein is determined using methods described herein. In someembodiments, the total NPOC in the sodium thiosulfate provided herein isdetermined by a) contacting the sodium thiosulfate with a predeterminedamount of an inorganic acid-containing aqueous solution to form anaqueous sample solution; b) removing precipitates from the aqueoussample solution; c) contacting the sample solution with a predeterminedamount of an oxidizer; and d) converting the organic carbon in thesample solution into carbon dioxide under a supercritical wateroxidation (SCWO) condition.

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.05 ppm of mercury. In some embodiments,the mercury content in the sodium thiosulfate provided herein isdetermined using ICP-MS. In some embodiments, the mercury content in thesodium thiosulfate provided herein is determined using ICP-OES. In someembodiments, the mercury content in the sodium thiosulfate providedherein is determined according to Method 261 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 2 ppm of aluminum. In some embodiments,the aluminum content in the sodium thiosulfate provided herein isdetermined using ICP-MS. In some embodiments, the aluminum content inthe sodium thiosulfate provided herein is determined using ICP-OES. Insome embodiments, the aluminum content in the sodium thiosulfateprovided herein is determined according to Method 206 in USP XXXII(2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 3 ppm of arsenic. In some embodiments,the arsenic content in the sodium thiosulfate provided herein isdetermined using ICP-MS. In some embodiments, the arsenic content in thesodium thiosulfate provided herein is determined using ICP-OES. In someembodiments, the arsenic content in the sodium thiosulfate providedherein is determined according to Method 211 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.003% by weight of selenium. In someembodiments, the selenium content in the sodium thiosulfate providedherein is determined using ICP-MS. In some embodiments, the seleniumcontent in the sodium thiosulfate provided herein is determined usingICP-OES. In some embodiments, the selenium content in the sodiumthiosulfate provided herein is determined according to Method 291 in USPXXXII (2009).

In yet another embodiment, the total aerobic count of microbial load inthe sodium thiosulfate provided herein is no greater than about 100Colony Forming Units per gram (CFU/g). The total aerobic count ofmicrobial load in the sodium thiosulfate provided herein is quantitatedaccording to Method 61 in USP XXXII (2009).

In yet another embodiment, the total yeast and mold count in the sodiumthiosulfate provided herein is no greater than about 20 CFU/g. The totalyeast and mold count in the sodium thiosulfate provided herein isquantitated according to Method 61 in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than about 0.02 Endotoxin Units per milligram(EU/mg), no greater than about 0.1 EU/mg, or no greater than about 0.25EU/mg of bacterial endotoxins. The amount of bacterial endotoxins in thesodium thiosulfate provided herein is quantitated according to Method 85in USP XXXII (2009).

In yet another embodiment, the sodium thiosulfate provided hereincontains no greater than 0.01% of a residual anti-caking agent.

In yet another embodiment, the sodium thiosulfate provided herein ischaracterized by one or more of the following:

containing no less than about 99% by weight and/or no greater than about100.5% by weight of sodium thiosulfate on an anhydrous basis determinedaccording to USP colormimetric assay;

containing no less than about 98% by weight and/or no greater than about102% by weight of sodium thiosulfate on an anhydrous basis determinedaccording to ion chromatography assay;

having a pH between about 6 to about 8 when measured in a 10% solutionat 25° C.;

having water content of about 32% to about 37% by weight;

having an appearance of colorless crystals;

having a clear and colorless appearance as a 10% solution;

having no odor;

having a positive identification test for sodium;

having a positive identification test for thiosulfate;

having no turbidy when mixed with ammonium oxalate TS;

having heavy metal content of no greater than about 10 ppm;

containing no greater than about 0.01% by weight of carbonate;

containing no greater than about 0.005% by weight of insoluble matter;

containing no greater than about 200 ppm of chloride;

containing no greater than about 0.001% by weight of sulfide;

containing no greater than about 0.05% or no greater than about 0.1% byweight of sulfite;

containing no greater than about 0.05%, no greater than about 0.1%, nogreater than about 0.25%, or no greater than about 0.5% by weight ofsulfate;

containing no greater than about 0.002% by weight of iron;

containing no greater than about 0.01% by weight of calcium;

containing no greater than about 0.005% by weight of potassium;

containing no greater than about 10 ppm, no greater than about 100 ppm,no greater than about 500 ppm, no greater than about 1000 ppm, or nogreater than 5000 ppm of organic volatile impurities;

having total NPOC of no greater than 60 ppb, no greater than about 2.5ppm, no greater than about 8 ppm, no greater than about 10 ppm, nogreater than about 20 ppm, no greater than about 25 ppm, or no greaterthan about 50 ppm;

containing no greater than about 0.05 ppm of mercury;

containing no greater than about 2 ppm of aluminum;

containing no greater than about 3 ppm of arsenic;

containing no greater than 0.001% by weight of lead;

containing no greater than about 0.002% by weight of nitrogen compounds(as N);

containing no greater than about 0.003% by weight of selenium;

containing no greater than 0.01% of a residual anti-caking agent;

having a total aerobic count of microbial load of no greater than about100 CFU/g;

having a total yeast and mold count of no greater than about 20 CFU/g;and

containing no greater than about 0.02 EU/mg, no greater than about 0.1EU/mg, or no greater than about 0.25 EU/mg of bacterial endotoxins.

In still another embodiment, the sodium thiosulfate provided herein ischaracterized by one or more of the following:

containing no less than about 99% by weight and/or no greater than about100.5% by weight of sodium thiosulfate on an anhydrous basis determinedaccording to USP colormimetric assay;

containing no less than about 98% by weight and/or no greater than about102% by weight of sodium thiosulfate on an anhydrous basis determinedaccording to ion chromatography assay;

having a pH between about 6 to about 8 when measured in a 10% solutionat 25° C.;

having water content of about 32% to about 37% by weight;

having an appearance of colorless crystals;

having a clear and colorless appearance as a 10% solution;

having no odor;

having a positive identification test for sodium;

having a positive identification test for thiosulfate;

having no turbidy when mixed with ammonium oxalate TS;

having heavy metal content of no greater than about 10 ppm;

containing no greater than about 0.01% by weight of carbonate;

containing no greater than about 0.005% by weight of insoluble matter;

containing no greater than about 200 ppm of chloride;

containing no greater than about 0.001% by weight of sulfide;

containing no greater than about 0.05% or no greater than about 0.1% byweight of sulfite;

containing no greater than about 0.05%, no greater than about 0.1%, nogreater than about 0.25%, or no greater than about 0.5% by weight ofsulfate;

containing no greater than about 0.002% by weight of iron;

containing no greater than about 0.01% by weight of calcium;

containing no greater than about 0.005% by weight of potassium;

containing no greater than about 10 ppm, no greater than about 100 ppm,no greater than about 500 ppm, no greater than about 1000 ppm, or nogreater than 5000 ppm of organic volatile impurities;

having total NPOC of no greater than 60 ppb, no greater than about 2.5ppm, no greater than about 8 ppm, no greater than about 10 ppm, nogreater than about 20 ppm, no greater than about 25 ppm, or no greaterthan about 50 ppm;

containing no greater than about 0.05 ppm of mercury;

containing no greater than about 2 ppm of aluminum;

containing no greater than about 3 ppm of arsenic;

containing no greater than 0.001% by weight of lead;

containing no greater than about 0.002% by weight of nitrogen compounds(as N);

containing no greater than about 0.003% by weight of selenium;

having a total aerobic count of microbial load of no greater than about100 CFU/g;

having a total yeast and mold count of no greater than about 20 CFU/g;and

containing no greater than about 0.02 EU/mg, no greater than about 0.1EU/mg, or no greater than about 0.25 EU/mg of bacterial endotoxins.

In some embodiments, where the sodium thiosulfate is described as“containing no greater than” a certain amount of a particular material,the sodium thiosulfate does not contain a detectable amount of thematerial.

Methods of Maintaining Physiological Level of Thiosulfate

Provided herein are methods for maintaining physiological levels ofthiosulfate in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added to anunspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

Also provided herein are methods for maintaining physiological levels ofthiosulfate in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In one embodiment, the physiological level of thiosulfate in saidsubject is no more than about 100 micromolar. In another embodiment, thephysiological level of thiosulfate in said subject is no more than about10 micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is between about 500 nanomolar and about 10micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is between about 1 micromolar and about 5micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is about 3 micromolar.

In one embodiment, the concentration of thiosulfate in saidthiosulfate-spiked dialysate is no more than 100 micromolar. In anotherembodiment, the concentration of thiosulfate in said thiosulfate-spikeddialysate is no more than about 10 micromolar. In yet anotherembodiment, the concentration of thiosulfate in said thiosulfate-spikeddialysate is between about 500 nanomolar and about 10 micromolar. In yetanother embodiment, the concentration of thiosulfate in saidthiosulfate-spiked dialysate is between about 1 micromolar and about 5micromolar. In yet another embodiment, the concentration of thiosulfatein said thiosulfate-spiked dialysate is about 3 micromolar.

In some embodiments, the aqueous solution comprising sodium thiosulfatecomprises no more than about 10 mg/L, about 50 mg/L, about 100 mg/L,about 150 mg/L, about 200 mg/L, about 250 mg/L, about 300 mg/L, about350 mg/L, about 400 mg/L, about 450 mg/mL, or about 500 mg/L of sodiumthiosulfate.

In some embodiments, the water comprises no more than about 10 mg/L,about 50 mg/L, about 100 mg/L, about 150 mg/L, about 200 mg/L, about 250mg/L, about 300 mg/L, about 350 mg/L, about 400 mg/L, about 450 mg/mL,or about 500 mg/L of thiosulfate.

In one embodiment, the aqueous solution comprising sodium thiosulfate isadded to said unspiked dialysate through a valve that is attached todialysate tubing at a location before said tubing connects to thedialyzer. In another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 200 mL/min and about 1000mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 300 mL/min and about 900mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 400 mL/min and about 800mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 500 mL/min and about 700mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate about 600 mL/min.

In one embodiment, the aqueous solution comprising sodium thiosulfate isadded through the valve to the unspiked dialysate at a rate betweenabout 0 mL/hr and about 750 mL/hr, at a rate between about 50 mL/hr andabout 650 mL/hr, at a rate between about 100 mL/hr and about 550 mL/hr,at a rate between about 150 mL/hr and about 450 mL/hr, or at a ratebetween about 200 mL/hr and about 350 mL/hr. In another embodiment, theaqueous solution comprising sodium thiosulfate is added through thevalve to the unspiked dialysate at a rate about 250 mL/hr.

In yet another embodiment, the pH of said thiosulfate-spiked dialysateis between about 7.0 and about 8.0. In yet another embodiment, the pH ofsaid thiosulphate-spiked dialysate is between about 7.1 and about 8.0.In yet another embodiment, the pH of said thiosulfate-spiked dialysateis between about 7.3 and about 8.0. In yet another embodiment, the pH ofsaid sodium thiosulfate-spiked dialysate is between about 7.3 and about7.5. In yet another embodiment, the pH of said sodium thiosulfate-spikeddialysate is about 7.4.

In yet another embodiment, said subject is a human with chronic renalfailure. In another embodiment, the said subject is a human with acuterenal failure.

In yet another embodiment, said subject undergoes hemodialysis from oneto ten times per week. In yet another embodiment, the said subjectundergoes hemodialysis from three to seven times per week.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

Methods of Prevention 1. Methods of Preventing Atherosclerosis

In some embodiments, provided herein are methods for preventingatherosclerosis in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added to anunspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, further provided herein are methods for preventingatherosclerosis in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

2. Methods of Preventing Myocardial Infarction

In some embodiments, provided herein are methods for preventingmyocardial infarction in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added to anunspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, further provided herein are methods for preventingmyocardial infarction in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

3. Methods of Preventing Sudden Cardiac Death

In some embodiments, provided herein are methods for preventing suddencardiac death in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.

In some embodiments, further provided herein are methods for preventingsudden cardiac death in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

4. Methods of Preventing Stroke

In some embodiments, provided herein are methods for preventing strokein a subject undergoing dialysis, comprising intradialyticallycontacting said subject's blood with a dialyzer membrane that is also incontact with a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, further provided herein are methods for preventingstroke in a subject undergoing hemodialysis, comprisingintradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

5. Methods of Preventing Cardiovascular Disease

In some embodiments, provided herein are methods for preventingcardiovascular disease that is characterized by tissue ischemiaincluding angina, cerebral vasospasm, claudication, critical limbischemia, peripheral vascular disease, and sickle cell crisis in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a dialyzer membrane that is also in contactwith a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, further provided herein are methods for preventingcardiovascular disease that is characterized by tissue ischemiaincluding angina, cerebral vasospasm, claudication, critical limbischemia, peripheral vascular disease, and sickle cell crisis in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a thiosulfate-spiked dialysate, wherein anaqueous solution comprising sodium thiosulfate is added to an unspikeddialysate as the unspiked dialysate flows from a dialysis machine to adialyzer membrane, wherein said unspiked dialysate comprises a mixtureof water, an acid concentrate solution, and a bicarbonate concentratesolution, and wherein said thiosulfate-spiked dialysate has a pH greaterthan about 7.0.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

6. Methods of Preventing High Blood Pressure, Pulmonary Hypertension,and Renal Hypertension

In some embodiments, provided herein are methods for preventing highblood pressure, pulmonary hypertension, and renal hypertension in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a dialyzer membrane that is also in contactwith a thiosulfate-spiked dialysate, wherein an aqueous solutioncomprising sodium thiosulfate is added to said unspiked dialysate as theunspiked dialysate flows from a dialysis machine to a dialyzer membrane,wherein said unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In some embodiments, further provided herein are methods for preventinghigh blood pressure, pulmonary hypertension, and renal hypertension in asubject undergoing dialysis, comprising intradialytically contactingsaid subject's blood with a thiosulfate-spiked dialysate, wherein anaqueous solution comprising sodium thiosulfate is added to an unspikeddialysate as the unspiked dialysate flows from a dialysis machine to adialyzer membrane, wherein said unspiked dialysate comprises a mixtureof water, an acid concentrate solution, and a bicarbonate concentratesolution, and wherein said thiosulfate-spiked dialysate has a pH greaterthan about 7.0.

In some embodiments, the pulmonary hypertension is neonatal pulmonaryhypertension, primary pulmonary hypertension, or secondary pulmonaryhypertension.

In one embodiment, the subject is a mammal. In another embodiment, thesubject is a human.

In certain embodiments, the methods provided herein return and/ormaintain the subject's plasma levels of thiosulfate to normalphysiological levels.

In certain embodiments, the embodiments in paragraphs [00118]-[00127]apply to all methods provided herein.

In one embodiment, the physiological level of thiosulfate in saidsubject is no more than about 100 micromolar. In another embodiment, thephysiological level of thiosulfate in said subject is no more than about10 micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is between about 500 nanomolar and about 10micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is between about 1 micromolar and about 5micromolar. In yet another embodiment, the physiological level ofthiosulfate in said subject is about 3 micromolar.

In one embodiment, the concentration of thiosulfate in saidthiosulfate-spiked dialysate is no more than about 100 micromolar. Inanother embodiment, the concentration of thiosulfate in saidthiosulfate-spiked dialysate is no more than about 10 micromolar. In yetanother embodiment, the concentration of thiosulfate in saidthiosulfate-spiked dialysate is between about 500 nanomolar and about 10micromolar. In yet another embodiment, the concentration of thiosulfatein said thiosulfate-spiked dialysate is between about 1 micromolar andabout 5 micromolar. In yet another embodiment, the concentration ofthiosulfate in said thiosulfate-spiked dialysate is about 3 micromolar.

In some embodiments, the aqueous solution comprising sodium thiosulfatecomprises no more than about 10 mg/L, about 50 mg/L, about 100 mg/L,about 150 mg/L, about 200 mg/L, about 250 mg/L, about 300 mg/L, about350 mg/L, about 400 mg/L, about 450 mg/mL, or about 500 mg/L of sodiumthiosulfate.

In some embodiments, the water comprises no more than about 10 mg/L,about 50 mg/L, about 100 mg/L, about 150 mg/L, about 200 mg/L, about 250mg/L, about 300 mg/L, about 350 mg/L, about 400 mg/L, about 450 mg/mL,or about 500 mg/L of thiosulfate.

In one embodiment, the aqueous solution comprising sodium thiosulfate isadded to said unspiked dialysate through a valve that is attached todialysate tubing at a location before said tubing connects to thedialyzer. In another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 200 mL/min and about 1000mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 300 mL/min and about 900mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 400 mL/min and about 800mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate between about 500 mL/min and about 700mL/min. In yet another embodiment, said unspiked dialysate flows throughsaid dialysis tubing at a rate about 600 mL/min.

In one embodiment, the aqueous solution comprising sodium thiosulfate isadded through the valve to the unspiked dialysate at a rate betweenabout 0 mL/hr and about 750 mL/hr, at a rate between about 50 mL/hr andabout 650 mL/hr, at a rate between about 100 mL/hr and about 550 mL/hr,at a rate between about 150 mL/hr and about 450 mL/hr, or at a ratebetween about 200 mL/hr and about 350 mL/hr. In another embodiment, theaqueous solution comprising sodium thiosulfate is added through thevalve to the unspiked dialysate at a rate about 250 mL/hr.

In yet another embodiment, the pH of said thiosulfate-spiked dialysateis between about 7.0 and about 8.0. In yet another embodiment, the pH ofsaid thiosulfate-spiked dialysate is between about 7.1 and about 8.0. Inyet another embodiment, the pH of said thiosulfate-spiked dialysate isbetween about 7.3 and about 8.0. In yet another embodiment, the pH ofsaid thiosulfate-spiked dialysate is between about 7.3 and about 7.5. Inyet another embodiment, the pH of said thiosulfate-spiked dialysate isabout 7.4.

In yet another embodiment, the said subject is a human with chronicrenal failure. In another embodiment, the said subject is a human withacute renal failure.

In yet another embodiment, the said subject undergoes hemodialysis fromone to ten times per week. In yet another embodiment, the said subjectundergoes hemodialysis from three to seven times per week.

In one embodiment, the thiosulfate-spiked dialysate has less than about10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about3%, about 2%, about 1%, about 0.5%, or about 0.1% decomposition ofthiosulfate as reflected by sulfate, sulfide, and sulfite contentmeasured in a sample taken from Detection Point “pre” (100) or Detectionpoint “post” (110).

Methods of Administration

In some embodiments, provided herein are methods for administeringsodium thiosulfate to a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added tosaid unspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysate comprisea mixture of water, an acid concentrate solution, and a bicarbonateconcentrate solution, and wherein said thiosulfate-spiked dialysate hasa pH greater than about 7.0.

In some embodiments, further provided herein are methods foradministering sodium thiosulfate to a subject undergoing hemodialysis,comprising intradialytically contacting said subject's blood with athiosulfate-spiked dialysate, wherein an aqueous solution comprisingsodium thiosulfate is added to an unspiked dialysate as the unspikeddialysate flows from a dialysis machine to a dialyzer membrane, whereinsaid unspiked dialysate comprises a mixture of water, an acidconcentrate solution, and a bicarbonate concentrate solution, andwherein said thiosulfate-spiked dialysate has a pH greater than about7.0.

In one embodiment, the thiosulfate-spiked dialysate has less than about10%, about 9%, about 8%, about 7%, about 6%, about 5%, about 4%, about3%, about 2%, about 1%, about 0.5%, or about 0.1% decomposition ofthiosulfate as reflected by sulfate, sulfide, and sulfite contentmeasured in a sample taken from Detection Point “pre” (100) or Detectionpoint “post” (110).

Combination Therapy

In some embodiments, the sodium thiosulfate provided herein may also becombined or used in combination with other therapeutic agents useful inthe treatment and/or prevention of the diseases and conditions providedherein.

As used herein, the term “in combination” includes the use of more thanone therapy (e.g., one or more prophylactic and/or therapeutic agents).However, the use of the term “in combination” does not restrict theorder in which therapies (e.g., prophylactic and/or therapeutic agents)are administered to a subject with a disease or disorder. A firsttherapy (e.g., a prophylactic or therapeutic agent such as a compoundprovided herein) can be administered prior to (e.g., about 5 minutes,about 15 minutes, about 30 minutes, about 45 minutes, about 1 hour,about 2 hours, about 4 hours, about 6 hours, about 12 hours, about 24hours, about 48 hours, about 72 hours, about 96 hours, about 1 week,about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, about 6weeks, about 8 weeks, or about 12 weeks before), concomitantly with, orsubsequent to (e.g., about 5 minutes, about 15 minutes, about 30minutes, about 45 minutes, about 1 hour, about 2 hours, about 4 hours,about 6 hours, about 12 hours, about 24 hours, about 48 hours, about 72hours, about 96 hours, about 1 week, about 2 weeks, about 3 weeks, about4 weeks, about 5 weeks, about 6 weeks, about 8 weeks, or about 12 weeksafter) the administration of a second therapy (e.g., a prophylactic ortherapeutic agent) to the subject. Triple therapy is also contemplatedherein.

As used herein, the term “synergistic” includes a combination of thesodium thiosulfate provided herein and another therapy (e.g., aprophylactic or therapeutic agent) which has been or is currently beingused to treat, prevent, or manage a disease or disorder, which is moreeffective than the additive effects of the therapies. A synergisticeffect of a combination of therapies (e.g., a combination ofprophylactic or therapeutic agents) permits the use of lower dosages ofone or more of the therapies and/or less frequent administration of saidtherapies to a subject with a disorder. The ability to utilize lowerdosages of a therapy (e.g., a prophylactic or therapeutic agent) and/orto administer said therapy less frequently reduces the toxicityassociated with the administration of said therapy to a subject withoutreducing the efficacy of said therapy in the prevention or treatment ofa disorder). In addition, a synergistic effect can result in improvedefficacy of agents in the prevention or treatment of a disorder.Finally, a synergistic effect of a combination of therapies (e.g., acombination of prophylactic or therapeutic agents) may avoid or reduceadverse or unwanted side effects associated with the use of eithertherapy alone.

The sodium thiosulfate provided herein can be administered incombination or alternation with another therapeutic agent. Incombination therapy, effective dosages of two or more agents areadministered together, whereas in alternation or sequential-steptherapy, an effective dosage of each agent is administered serially orsequentially. The dosages given will depend on absorption, inactivationand excretion rates of the drug as well as other factors known to thoseof skill in the art. It is to be noted that dosage values will also varywith the severity of the condition to be alleviated. It is to be furtherunderstood that for any particular subject, specific dosage regimens andschedules should be adjusted over time according to the individual needand the professional judgment of the person administering or supervisingthe administration of the compositions.

The sodium thiosulfate provided herein can be administered incombination with other classes of compounds, including, but not limitedto, endothelin converting enzyme (ECE) inhibitors, such asphosphoramidon; thromboxane receptor antagonists, such as ifetroban;potassium channel openers; thrombin inhibitors, such as hirudin; growthfactor inhibitors, such as modulators of PDGF activity; plateletactivating factor (PAF) antagonists; anti-platelet agents, such asGPIIb/IIIa blockers (e.g., abciximab, eptifibatide, and tirofiban),P2Y(AC) antagonists (e.g., clopidogrel, ticlopidine and CS-747), andaspirin; anticoagulants, such as warfarin; low molecular weightheparins, such as enoxaparin; Factor VIIa Inhibitors and Factor XaInhibitors; renin inhibitors; neutral endopeptidase (NEP) inhibitors;vasopeptidase inhibitors (dual NEP-ACE inhibitors), such as omapatrilatand gemopatrilat; HMG CoA reductase inhibitors, such as pravastatin,lovastatin, atorvastatin, simvastatin, NK-104 (a.k.a. itavastatin,nisvastatin, or nisbastatin), and ZD-4522 (also known as rosuvastatin,atavastatin, or visastatin); squalene synthetase inhibitors; fibrates;bile acid sequestrants, such as questran; niacin; anti-atheroscleroticagents, such as ACAT inhibitors; MTP Inhibitors; calcium channelblockers, such as amlodipine besylate; potassium channel activators;alpha-adrenergic agents; beta-adrenergic agents, such as carvedilol andmetoprolol; antiarrhythmic agents; diuretics, such as chlorothiazide,hydrochlorothiazide, flumethiazide, hydroflumethiazide,bendroflumethiazide, methylchlorothiazide, trichloromethiazide,polythiazide, benzothiazide, ethacrynic acid, ticrynafen,chlorthalidone, furosenide, muzolimine, bumetanide, triamterene,amiloride, and spironolactone; thrombolytic agents, such as tissueplasminogen activator (tPA), recombinant tPA, streptokinase, urokinase,prourokinase, and anisoylated plasminogen streptokinase activatorcomplex (APSAC); anti-diabetic agents, such as biguanides (e.g.,metformin), glucosidase inhibitors (e.g., acarbose), insulins,meglitinides (e.g., repaglinide), sulfonylureas (e.g., glimepiride,glyburide, and glipizide), thiozolidinediones (e.g., troglitazone,rosiglitazone, and pioglitazone), and PPAR-gamma agonists;mineralocorticoid receptor antagonists, such as spironolactone andeplerenone; growth hormone secretagogues; aP2 inhibitors;phosphodiesterase inhibitors, such as PDE III inhibitors (e.g.,cilostazol) and PDE V inhibitors (e.g., sildenafil, tadalafil, andvardenafil); protein tyrosine kinase inhibitors; antiinflammatories;antiproliferatives, such as methotrexate, FK506 (tacrolimus),mycophenolate mofetil; chemotherapeutic agents; immunosuppressants;anticancer agents and cytotoxic agents (e.g., alkylating agents, such asnitrogen mustards, alkyl sulfonates, nitrosoureas, ethylenimines, andtriazenes); antimetabolites, such as folate antagonists, purineanalogues, and pyrimidine analogues; antibiotics, such asanthracyclines, bleomycins, mitomycin, dactinomycin, and plicamycin;enzymes, such as L-asparaginase; farnesyl-protein transferaseinhibitors; hormonal agents, such as glucocorticoids (e.g., cortisone),estrogens/antiestrogens, androgens/antiandrogens, progestins, andluteinizing hormone-releasing hormone antagonists, and octreotideacetate; microtubule-disruptor agents, such as ecteinascidins;microtubule-stabilizing agents, such as pacitaxel, docetaxel, andepothilones A-F; plant-derived products, such as vinca alkaloids,epipodophyllotoxins, and taxanes; and topoisomerase inhibitors;prenyl-protein transferase inhibitors; and cyclosporins; steroids, suchas prednisone and dexamethasone; cytotoxic drugs, such as azathioprineand cyclophosphamide; TNF-alpha inhibitors, such as tenidap; anti-TNFantibodies or soluble TNF receptor, such as etanercept, rapamycin, andleflunimide; cyclooxygenase-2 (COX-2) inhibitors, such as celecoxib androfecoxib; and miscellaneous agents such as, sodium nitrite,hydroxyurea, procarbazine, mitotane, hexamethylmelamine, gold compounds,low-molecular weight medications, low-molecular weight vitamins, andplatinum coordination complexes, such as cisplatin, satraplatin, andcarboplatin.

The sodium thiosulfate provided herein can be administered incombination with other solutes that are naturally present in human bloodincluding copper, fluoride, iodine, iron, manganese, magnesium, nitrite,phosphorus, selenium, and zinc.

The disclosure will be further understood by the following non-limitingexamples.

EXAMPLES

As used herein, the symbols and conventions used in these experiments,processes, schemes and examples, regardless of whether a particularabbreviation is specifically defined, are consistent with those used inthe contemporary scientific literature, for example, the Journal of theAmerican Chemical Society or the Journal of Biological Chemistry.Specifically, but without limitation, the following abbreviations may beused in the examples and throughout the specification: g (grams); mg(milligrams); mL (milliliters); μL, (microliters); mM (millimolar); μM(micromolar); nM (nanomolar); mmol (millimoles); eq. (equivalent); hr orhrs (hours); min (minutes).

For all of the following experiments and the following example, standardwork-up and purification methods known to those skilled in the art canbe utilized. Unless otherwise indicated, all temperatures are expressedin ° C. (degrees Centigrade). All reactions conducted at roomtemperature unless otherwise noted. Methodologies illustrated in thefollowing examples are intended to exemplify the applicable chemistrythrough the use of specific examples and are not indicative of the scopeof the invention.

Stability Experiments

Results of the following stability experiments (Example 1 to 4)exemplify the instability of thiosulfate in aqueous solution when acidis added and also the instability of thiosulfate when mixed with asolution comprising an acid concentrate solution and a bicarbonateconcentrate solution in the preparation of a dialysate for dialysis.

Concentration of thiosulfate in samples was assayed by ionchromatography. The ion chromatograph was equipped with anelectrochemical conductivity detector and a Dionex IonPacAS12Aanalytical column. The sodium thiosulfate content in the samples testedwas calculated against an external sodium thiosulfate standard. USPSodium Thiosulfate Reference Standard (Item Number 1615107) was thetesting standard (United States Pharmacopeia. Rockville, Md.).

Example 1

The material safety data sheet for sodium thiosulfate indicates that thechemical decomposes on contact with acid (Material safety data sheetaccessed online athttp://www.thiosulfate.info/downloads/sodiumthiosulfate_msds.pdf).

Example 1 was performed to determine the stability of sodium thiosulfatein an aqueous solution when acid is added. A 60 mg sample of sodiumthiosulfate was transferred into a 50 mL volumetric flask. 2 mL of 0.1 Nhydrochloric acid was added to the flask. The flask was capped andheated at 80° C. for approximately 24 hours. The flask was subsequentlycooled to ambient temperature. 2 mL of 0.1 N sodium hydroxide was addedto neutralize the acid, and deionized water was added to bring thevolume to 50 mL. The percentage of thiosulfate degradation in thissample was 28.6%. Consistent with published information about thereaction between acid and thiosulfate (available online athttps://www.quora.com/Why-does-sodium-thiosulphate-react-with-hydrochloric-acid),this result confirms that sodium thiosulfate decomposes when exposed toacid.

Example 2

Example 2 was performed to determine the stability of sodium thiosulfatein dialysate bicarbonate concentrate solution. At room temperature,12500 mg sodium thiosulfate (50 mL of 250 mg/mL solution) was added to7,700 mL of dialysate bicarbonate concentrate solution. The thiosulfateconcentration of the dialysate bicarbonate concentrate solution wasanalyzed by ion chromatography 1) before addition of sodium thiosulfate;2) 5 minutes after the addition of sodium thiosulfate; and 3) 2 hoursafter the addition of sodium thiosulfate. The results presented in Table1 and Table 2 show that thiosulfate is stable when added to dialysatebicarbonate concentrate solution since the concentration of sodiumthiosulfate did not decline over time and the concentrations ofdegradation products sulfate, sulfite, and sulfide did not increase overtime.

TABLE 1 Sodium Thiosulfate Concentration in Dialysate BicarbonateConcentrate Expected Measured Sodium Sodium Thiosulfate Thiosulfate %Sample Concentration Concentration Recovery Dialysate Bicarbonate 0 NoneDetected NA Concentrate Solution Dialysate Bicarbonate 1.61 mg/mL 1.65mg/mL 102% Concentrate + Sodium Thiosulfate after 5 Minutes DialysateBicarbonate 1.61 mg/mL 1.65 mg/mL 102% Concentrate + Sodium ThiosulfateSolution after 2 Hours

TABLE 2 Sulfate, Sulfide, and Sulfite Concentrations in DialysateBicarbonate Concentrate + Sodium Thiosulfate Sulfate Sulfite SulfideConcentration Concentration Concentration Sample (μg/mL) (μg/mL) (μg/mL)Dialysate Bicarbonate 3.7 4.4 <2.5 μg/mL Concentrate Solution DialysateBicarbonate 4.4 5.9 <2.5 μg/mL Concentrate + Sodium Thiosulfate after 5Minutes Dialysate Bicarbonate 4.3 5.4 <2.5 μg/mL Concentrate + SodiumThiosulfate Solution after 2 Hours

Example 3

Example 3 was performed to further determine the stability ofthiosulfate in the mixture of sodium thiosulfate and dialysatebicarbonate concentrate solution from Example 2 when mixed with an acidconcentrate solution within a dialysis machine. A dialysis machine mixedthe dialysate bicarbonate concentrate solution (with sodium thiosulfateadded from Example 2), an acid concentrate solution and purified wateras the dialysis machined mixes dialysate in clinical practice, with thedilution ratio of 1 part of the acid concentrate solution, 1.72 parts ofthe bicarbonate concentrate solution, and 42.38 parts of purified water.The dialysis machine used for this experiment was a Fresenius 2008Khemodialysis machine (Fresenius Medical Care, Waltham, Mass.). Themachine was primed in bypass mode (dialysate and ultrafiltration ratesset at zero) using normal saline. After priming, the hemodialysismachine was run in “Therapy Mode” with the following settings: bloodflow rate 300 mL/minute, dialysate flow rate 600 mL/minute,ultrafiltration rate 0 mL/minute, and ultrafiltration time 25 minutes. Asample of the mixed dialysate was collected as it exited the dialysismachine and analyzed by ion chromatography.

The results presented in Table 3 show that thiosulfate in the dialysatebicarbonate concentrate solution almost completely decomposed in theprocess of mixing with an acid concentrate solution within the dialysismachine.

TABLE 3 Thiosulfate Concentration in Dialysate after Mixing withinHemodialysis Machine Expected Thiosulfate Thiosulfate Concentration %Sample Concentration by Assay Recovery Mixed Dialysate + Sodium 0.0608mg/L 0.001824 3% Thiosulfate

Example 4

Example 4 was performed to determine the stability of thiosulfate whensodium thiosulfate is added to the dialysate after the dialysate hasbeen prepared within a Fresenius 2008K hemodialysis machine (FreseniusMedical Care, Waltham, Mass.). Dialysate bicarbonate concentratesolution was prepared by adding 1 package of Centrisol® MB-330 SeriesSodium Bicarbonate Concentrate powder (650 g) to 7.7 liters of purifiedwater.

The hemodialysis machine mixed the bicarbonate concentrate solution andacid concentrate solution with the dilution ratio of 1 part of an acidconcentrate solution, 1.72 parts of a bicarbonate concentrate solution,and 42.38 parts of purified water. The machine was primed in bypass mode(dialysate and ultrafiltration rates set at zero) using normal saline.After priming, the hemodialysis machine was run in “Therapy Mode” withthe following settings: blood flow rate 300 mL/minute, dialysate flowrate 600 mL/minute, ultrafiltration rate 0 mL/minute.

An aqueous solution of sodium thiosulfate was prepared by dissolving 25mg of sodium thiosulfate in 1 liter of purified water. This sodiumthiosulfate solution complied with the AAMI quality specification forsulfate (and thiosulfate) since the resulting sodium thiosulfatesolution had a thiosulfate anion concentration of approximately 17.72mg/L. The sodium thiosulfate solution was infused directly intodialysate tubing between the hemodialysis machine and the dialyzer via avalve (Fresensius Dialysate Sample Valve: part #650993) using an Alaris®IV Infusion Pump (Model 8100, CareFusion, San Diego, Calif.). This valvewas placed in the dialysate tubing approximately eight inches upstreamof the dialyzer (pre-filter). Two sampling ports were placed four inchesupstream (pre-dialyzer sampling port) and ten inches downstream(post-dialyzer sampling port) from the dialyzer to collect samples ofdialysate for nitrate assay by ion chromatography.

The infusion pump infused the sodium thiosulfate solution into thetubing through the valve at a rate of 250 mL/hour (4.16 mL/minute).

Normal saline flowed into the dialyzer at a rate of 300 mL/minute fromthe Arterial line and exited the dialyzer through the Venous line.Samples of saline were collected from the venous side of the dialyzer.

The results presented in Table 4 show that thiosulfate is stable when asodium thiosulfate solution mixed with dialysate within dialysate tubingwhen infused into the tubing at a location that is between thehemodialysis machine and the dialyzer membrane.

TABLE 4 Thiosulfate Concentration in Dialysate Before and After SodiumThiosulfate Solution is Added to Dialysate within Dialysate TubingBefore Dialysate Contacting the Dialyzer Membrane ThiosulfateThiosulfate Concentration* Concentration* Before the After the Additionof Addition of Sodium Sodium Thiosulfate Thiosulfate Sample (Time = 0Min) (Time = 60 Min) Dialysate + Sodium 0 4.04 μM Thiosulfate Solution(Before Dialyzer) Dialysate + Sodium 0 2.20 μM Thiosulfate Solution(After Dialyzer) Saline Solution 0 1.62 μM (After Dialyzer) *Averageresults from two samples

The results presented in Table 4 show that thiosulfate can either passalong or pass through a dialyzer if the thiosulfate is added to theunspiked dialysate from the hemodialysis machine at a location betweenthe hemodialysis machine and the dialyzer membrane.

The example set forth above are provided to give those of ordinary skillin the art with a complete disclosure and description of how to make anduse the claimed embodiments, and are not intended to limit the scope ofwhat is disclosed herein. Modifications that are obvious to persons ofskill in the art are intended to be within the scope of the followingclaims. All publications, patents, and patent applications cited in thisspecification are incorporated herein by reference as if each suchpublication, patent or patent application were specifically andindividually indicated to be incorporated herein by reference.

What is claimed is:
 1. A method for maintaining physiological levels ofthiosulfate in a subject undergoing hemodialysis; preventing myocardialinfarction in a subject undergoing dialysis; preventing sudden cardiacdeath in a subject undergoing dialysis; preventing stroke in a subjectundergoing dialysis; preventing cardiovascular disease that ischaracterized by tissue ischemia in a subject undergoing dialysis;preventing high blood pressure in a subject undergoing dialysis;preventing pulmonary hypertension in a subject undergoing dialysis;preventing renal hypertension in a subject undergoing dialysis; orpreventing atherosclerosis in a subject undergoing dialysis, comprisingintradialytically contacting said subject's blood with a dialyzermembrane that is also in contact with a thiosulfate-spiked dialysate,wherein an aqueous solution comprising sodium thiosulfate is added to anunspiked dialysate as the unspiked dialysate flows from a dialysismachine to a dialyzer membrane, wherein said unspiked dialysatecomprises a mixture of water, an acid concentrate solution, and abicarbonate concentrate solution, and wherein said thiosulfate-spikeddialysate has a pH greater than about 7.0.
 2. The method of claim 1,wherein the physiological level of thiosulfate in said subject is nomore than about 10 micromolar.
 3. The method of claim 1, wherein thephysiological level of thiosulfate in said subject is between about 500nanomolar and about 5 micromolar.
 4. The method of claim 1, wherein thephysiological level of thiosulfate in said subject is about 3micromolar.
 5. The method of claim 1, wherein the concentration ofthiosulfate in said thiosulfate-spiked dialysate is no more than about10 micromolar.
 6. The method of claim 1, wherein the concentration ofthiosulfate in said thiosulfate-spiked dialysate is between about 500nanomolar and about 5 micromolar.
 7. The method of claim 1, wherein theconcentration of thiosulfate in said thiosulfate-spiked dialysate isabout 3 micromolar.
 8. The method of claim 1, wherein said aqueoussolution comprising sodium thiosulfate comprises no more than about 300mg/L of sodium thiosulfate.
 9. The method of claim 1, wherein said watercomprises no more than about 200 mg/L of thiosulfate.
 10. The method ofclaim 1, wherein said aqueous solution comprising sodium thiosulfate isadded to said unspiked dialysate through a valve that is attached todialysate tubing at a location before said tubing connects to thedialyzer.
 11. The method of claim 10, wherein said unspiked dialysateflows through said dialysis tubing at a rate between about 500 mL/minand about 700 mL/min.
 12. The method of claim 10, wherein said unspikeddialysate flows through said dialysis tubing at a rate of about 600mL/min.
 13. The method of claim 10, wherein said aqueous solutioncomprising sodium thiosulfate is added through said valve to saidunspiked dialysate at a rate between about 100 mL/hr and about 550mL/hr.
 14. The method of claim 10, wherein said aqueous solutioncomprising sodium thiosulfate is added through said valve to saidunspiked dialysate at a rate of about 250 mL per hour.
 15. The method ofclaim 1, wherein the pH of said thiosulfate-spiked dialysate is betweenabout 7.3 and about 7.5.
 16. The method of claim 1, wherein the pH ofsaid thiosulfate-spiked dialysate is about 7.4.
 17. The method of claim1, wherein said subject is a human with chronic renal failure.
 18. Themethod of claim 1, wherein said subject is a human with acute renalfailure.
 19. The method of claim 1, wherein said subject undergoesdialysis from three to seven times per week.